T Type Thermocouples

Written by Nicholas Kamuda

K and T type thermocouples are the two most common types of thermocouples in handheld temperature measuring devices. However, thermocouples or contact probes are not commonly included in different kinds of IR thermometers, except from a few manufacturers (e.g., Radiant and Raytek). Only a few IR thermometers feature the option of connecting a K type or T type thermocouple one via a small port built into the device such as the TN305LC IR thermometer available from Metris Instruments.

The bulk of the popularity of thermocouples may be owed to their range and durability. Thermocouples consist of two different metals (usually alloys) that are connected to produce a small voltage when subjected to changes in temperature. The voltage, when amplified, can be interpreted as temperature data for the object that they thermocouple is in contact with.

Comparing K Type and T Type Thermocouples

K type thermocouples are popular because of their reliability and broad temperature range. They offer a decent degree of sensitivity for all temperatures between minus 200 and 1,200 ° Centigrade. Unlike other kinds of thermocouples, they use inexpensive metals (Ni-Al and Ni-Cr alloys) that stay calibrated across every range of temperatures.

T type thermocouples are more suited to low-temperature use. They use metals that are slightly more rare, but are more accurate than K type thermocouples at sub-zero temperatures. T type thermocouples use a copper-nickel alloy called constantan and pure copper for the conductors.